JP2023037170A - Method for producing diphosphorus pentasulfide composition - Google Patents

Abstract

A method for producing a phosphorus pentasulfide composition that achieves both high crystallinity and high recovery is provided.
The method includes a heating step of treating a raw material phosphorus pentasulfide composition at a temperature of 130° C. or more and lower than the melting point of the raw material phosphorus pentasulfide composition, and crystallization from the raw material phosphorus pentasulfide composition. A method for producing a phosphorus pentasulfide composition, which obtains a high crystallinity phosphorus pentasulfide composition having a high crystallinity.
[Selection drawing] Fig. 2

Description

The present invention relates to a method for producing a phosphorus pentasulfide composition. More specifically, it relates to a method for producing a phosphorus pentasulfide composition that is preferably used in a sulfide-based inorganic solid electrolyte.

Lithium ion batteries are generally used as power sources for small portable devices such as mobile phones and laptop computers. In addition to small portable devices, recently, lithium ion batteries have begun to be used as power sources for electric vehicles, power storage, and the like.

Lithium-ion batteries currently on the market use electrolytes containing flammable organic solvents. On the other hand, a lithium-ion battery in which the electrolyte is replaced with a solid electrolyte to make the battery solid (hereinafter also referred to as an all-solid-state lithium-ion battery) does not use a flammable organic solvent in the battery, so a safety device simplification, and it is considered to be excellent in manufacturing cost and productivity.

As a solid electrolyte material used for such a solid electrolyte, for example, a sulfide-based inorganic solid electrolyte material is known. As a method for producing a sulfide-based inorganic solid electrolyte material, a phosphorus pentasulfide composition containing diphosphorus pentasulfide (P ₂ S ₅ ) as a main component is treated with a material such as lithium sulfide. It is known.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2020-61304) describes a phosphorus pentasulfide composition having a crystallinity of 30% or more calculated from a spectrum obtained by X-ray diffraction measurement using CuKα rays. ing. In addition, a phosphorus pentasulfide composition having a crystallinity of 30% or more reduces the amount of low-boiling phosphorus sulfide compounds ( _P4S3 , _{P4S7 ,} etc.) in the _phosphorus pentasulfide composition. , which is obtained by vacuum heating or the like for improving crystallinity.

JP 2020-61304 A

However, when the production method in the above invention is adopted, the heating temperature is high, so the recovery rate of the phosphorus pentasulfide composition after production relative to the raw material phosphorus pentasulfide composition is low, and the production cost is high. There was a problem.

The present invention has been made in view of such circumstances, and is capable of producing a phosphorus pentasulfide composition having a high degree of crystallinity, and having a high recovery rate with respect to the raw material phosphorus pentasulfide composition. An object of the present invention is to provide a method for producing a diphosphorus sulfide composition.

The present inventors have made intensive studies to provide a method for producing a phosphorus pentasulfide composition that achieves both high crystallinity and high recovery. As a result, in the heating step for crystallizing the diphosphorus pentasulfide composition, the raw material diphosphorus pentasulfide composition is annealed at a low temperature below its melting point, so that the obtained phosphorus pentasulfide composition has a high The inventors have found that it is possible to achieve both a degree of crystallinity and a high recovery rate, leading to the present invention.

That is, according to the present invention,
a heating step of treating the starting diphosphorus pentasulfide composition at a temperature of 130° C. or higher and lower than the melting point of the starting diphosphorus pentasulfide composition;
Provided is a method for producing a phosphorus pentasulfide composition, which obtains a high crystallinity phosphorus pentasulfide composition having a higher degree of crystallinity than the raw material phosphorus pentasulfide composition.

According to the present invention, it is possible to provide a method for producing a phosphorus pentasulfide composition that achieves both high crystallinity and high recovery.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows an example of the structure of the lithium ion battery of embodiment which concerns on this invention. FIG. 2 shows X-ray diffraction spectra of phosphorus pentasulfide compositions obtained in Examples and Comparative Examples. FIG. 2 is a diagram showing an X-ray diffraction spectrum for explaining a method (peak separation method) for calculating the degree of crystallinity of the phosphorus pentasulfide composition of the embodiment according to the present invention. FIG. 4 is a diagram for explaining a baseline used when calculating the heat quantity of an endothermic peak; FIG. 2 is a diagram showing DSC curves on the high temperature side of the phosphorus pentasulfide compositions obtained in Examples and Comparative Examples. FIG. 2 is a diagram showing DSC curves on the low temperature side of the phosphorus pentasulfide compositions obtained in Examples and Comparative Examples.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in all the drawings, the same constituent elements are denoted by the same reference numerals, and the explanation thereof is omitted as appropriate. Also, the drawings are schematic diagrams and do not correspond to actual dimensional ratios. The numerical range "A to B" represents from A to B unless otherwise specified.

[Method for producing diphosphorus pentasulfide composition]
First, a method for producing a phosphorus pentasulfide composition according to this embodiment will be described.
The method for producing a diphosphorus pentasulfide composition according to the present embodiment is different from the conventional method for producing a diphosphorus pentasulfide composition. That is, the high-crystallinity diphosphorus pentasulfide composition according to the present embodiment is obtained by subjecting the raw material phosphorus pentasulfide composition to a heat treatment to convert the low boiling point phosphorus sulfide in the raw material phosphorus pentasulfide composition to It can be obtained for the first time by adopting a devised point in the manufacturing method such as a treatment to reduce the amount of compounds (P ₄ S ₃ , P ₄ S ₇ etc.).
However, the method for producing the diphosphorus pentasulfide composition according to the present embodiment can adopt various specific production conditions, for example, on the premise of adopting the above-described contrivances in the production method.

In the method for producing a diphosphorus pentasulfide composition according to the present embodiment, the raw material diphosphorus pentasulfide composition is heated at a temperature of 130° C. or higher and lower than the melting point of the raw material diphosphorus pentasulfide composition. and obtaining a high crystallinity phosphorus pentasulfide composition having a higher degree of crystallinity than the raw material phosphorus pentasulfide composition.
The method for producing the diphosphorus pentasulfide composition according to the present embodiment employs the above-described configuration to perform heating at a temperature below the melting point of the raw material diphosphorus pentasulfide composition. It is possible to minimize the evaporation of diphosphorus pentasulfide and effectively remove only the low-boiling phosphorus sulfide compounds _{( P4S3} , _{P4S7 ,} etc.).

Hereinafter, the method for producing the diphosphorus pentasulfide composition according to the present embodiment will be described more specifically.

(Heating process)
In the method _for producing a diphosphorus pentasulfide composition according to the present embodiment, a low-boiling phosphorus sulfide compound ( _P4S3 , P ₄ S _7, etc.) to improve the crystallinity of the starting phosphorus pentasulfide composition. As a result, a high-crystallinity phosphorus pentasulfide composition having a higher crystallinity than the raw material phosphorus pentasulfide composition according to the present embodiment can be obtained. Here, when the raw material phosphorus pentasulfide composition is heated, the component that does not evaporate and accumulates at the bottom of the container is usually the high crystallinity phosphorus pentasulfide composition according to the present embodiment.

Here, the lower limit of the heating temperature in the heating step is preferably 130° C. or higher, more preferably 150° C. or higher, and even more preferably 180° C. or higher. By setting the heating temperature to the above lower limit or higher, the crystallinity of the high-crystallinity phosphorus pentasulfide composition can be made more suitable.
The upper limit of the heating temperature in the heating step is preferably less than the melting point of the raw material diphosphorus pentasulfide composition, more preferably 250° C. or lower, and even more preferably 220° C. or lower. By setting the heating temperature to the above upper limit or less, the recovery rate of the high-crystallinity phosphorus pentasulfide composition can be made more suitable.
The melting point of the raw material phosphorus pentasulfide composition can be confirmed by a DSC curve described later.

In the method for producing a diphosphorus pentasulfide composition according to the present embodiment, the raw material diphosphorus pentasulfide composition is heat-treated in a temperature range of the above lower limit or more and the above upper limit or less to achieve high crystallinity and high It is possible to obtain a phosphorus pentasulfide composition that satisfies both recovery rates.
Although the reason for this is not necessarily clear, in the method for producing a phosphorus pentasulfide composition according to the present embodiment, the raw material phosphorus pentasulfide composition is heated to a temperature below the melting point to temporarily destabilize its structure. In order to easily change the glassy state of phosphorus pentasulfide to a more stable crystalline state, only low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S ₇ etc.) are removed to obtain diphosphorus pentasulfide It is believed that this is because the evaporation of phosphorus can be prevented to a minimum.
At present, it is believed that the crystallinity of the phosphorus pentasulfide composition calculated from the X-ray diffraction spectrum is closely related to the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material obtained from the phosphorus pentasulfide. It is considered. In addition, the higher the crystallinity of the phosphorus pentasulfide composition calculated from the X-ray diffraction spectrum, the higher the crystallinity of the phosphorus pentasulfide and the lower boiling point phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S ₇ etc.) is thought to be low. Therefore, vacuum heat _treatment or the like has been performed to remove low-boiling phosphorus sulfide compounds ( _P4S3 , _{P4S7 ,} etc.). However, since the heating was performed at a temperature higher than the melting point of the phosphorus pentasulfide composition (for example, 300° C.), part of the phosphorus pentasulfide contained in the phosphorus pentasulfide composition was also evaporated and recovered. rate may have declined.
On the other hand, in the method for producing a diphosphorus pentasulfide composition according to the present embodiment, since heating is performed at a temperature below the melting point of the raw material diphosphorus pentasulfide composition, It is possible to minimize evaporation and effectively remove only low boiling phosphorus sulfide compounds _{( P4S3} , _{P4S7 ,} etc.).
For the above reasons, the method for producing a phosphorus pentasulfide composition according to the present embodiment effectively removes the low-boiling phosphorus sulfide compound. is considered to be able to achieve both high crystallinity and high recovery.

In the method for producing a phosphorus pentasulfide composition according to the present embodiment, the upper limit of the recovery rate of the high crystallinity phosphorus pentasulfide composition is preferably 90% or more, more preferably 91% or more, and further Preferably it is 92% or more. When the recovery rate is equal to or higher than the lower limit, the production efficiency of the high crystallinity phosphorus pentasulfide composition can be improved.
Although the lower limit of the recovery rate is not particularly limited, it is preferably 99% or less, more preferably 98% or less, and still more preferably 97% or less. When the recovery rate is equal to or lower than the upper limit, the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S ₇ , etc.) in the raw material phosphorus pentasulfide composition can be reduced.
The recovery rate refers to the ratio of the mass of the high crystallinity phosphorus pentasulfide composition after heating to the mass of the raw material phosphorus pentasulfide composition, and can be calculated from the following formula (1).
Recovery rate (%) = (M _A /M _B ) x 100 (1)
M _A : mass (g) of the high crystallinity phosphorus pentasulfide composition
M _B : Mass (g) of raw material phosphorus pentasulfide composition

In the method for producing a diphosphorus pentasulfide composition according to the present embodiment, the lower limit of the heating time of the raw material diphosphorus pentasulfide composition in the heating step is preferably 0.5 hours or more, more preferably 3 hours or more, more preferably 5 hours or more, and particularly preferably 6 hours or more. When the heating time is equal to or longer than the above lower limit, the crystallinity of the high crystallinity phosphorus pentasulfide composition can be made more suitable.
The upper limit of the heating time is preferably 24 hours or less, more preferably 12 hours or less, still more preferably 10 hours or less, and particularly preferably 8 hours or less. When the heating time is equal to or less than the above upper limit, the recovery rate of the high crystallinity phosphorus pentasulfide composition can be made more suitable.

In the method for producing the diphosphorus pentasulfide composition according to the present embodiment, the heating temperature and the heating time are determined by the treatment amount of the raw material diphosphorus pentasulfide composition and the high-crystallinity diphosphorus pentasulfide composition to be produced. It can be appropriately determined depending on the recovery rate, physical properties, etc. required for the product. Among them, the heating temperature is 180° C. or higher and 220° C. or lower and the heating time is 6 hours or longer and 8 hours or shorter, from the viewpoint of the balance between the recovery rate and the crystallinity of the high-crystallinity phosphorus pentasulfide composition. is preferred.

In the method for producing a diphosphorus pentasulfide composition according to the present embodiment, the heating step is preferably carried out in an inert gas atmosphere or a vacuum atmosphere, more preferably in an inert gas atmosphere. By adopting the above configuration, it is possible to prevent reaction with each component in the air or moisture, and to prevent generation of impurities in the phosphorus pentasulfide composition. In particular, performing the heating step in an inert gas atmosphere is preferable from the viewpoint of facilitating maintenance of the atmosphere in the heating apparatus. The vacuum atmosphere means that the pressure in the heating device is −0.01 MPa or less.

Examples of the inert gas in the heating step include argon gas, helium gas, and nitrogen gas. Among these, argon gas is particularly preferred. These inert gases preferably have a high purity in order to prevent contamination of the product with impurities. °C or less is particularly preferred. The method of introducing the inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with an inert gas atmosphere. methods and the like.

(Preparation process)
The method for producing a phosphorus pentasulfide composition according to the present embodiment may include a preparation step of preparing a raw material phosphorus pentasulfide composition before the heating step.
The starting diphosphorus pentasulfide composition to be used as a raw material is not particularly limited, and commercially available diphosphorus pentasulfide (P ₂ S ₅ ) may be used as it is, or a generally known production of diphosphorus pentasulfide may be used. A raw phosphorus pentasulfide composition obtained using the method may also be used.

[Phosphorus pentasulfide composition]
Next, a high crystallinity phosphorus pentasulfide composition (hereinafter also referred to as a phosphorus pentasulfide composition) obtained by the method for producing a phosphorus pentasulfide composition according to the present embodiment will be described.

The diphosphorus pentasulfide composition according to the present embodiment preferably has a lower limit of crystallinity of 40% or more, more preferably 40% or more, calculated from a spectrum obtained by X-ray diffraction using CuKα rays as a radiation source. is 45% or more, more preferably 50% or more, particularly preferably 55% or more.
Furthermore, the upper limit of the crystallinity is preferably 80% or less, more preferably 76% or less, still more preferably 73% or less, and particularly preferably 70% or less.

The diphosphorus pentasulfide composition according to the present embodiment has a crystallinity calculated from the X-ray diffraction spectrum that is equal to or higher than the above lower limit, and is a sulfide system produced using the obtained diphosphorus pentasulfide composition. The lithium ion conductivity of the inorganic solid electrolyte material can be improved.
In addition, the diphosphorus pentasulfide composition according to the present embodiment has a crystallinity calculated from the X-ray diffraction spectrum of not more than the above upper limit value, so that the lithium ion conductivity is preferably maintained while five The recovery rate of the diphosphorus sulfide composition can be made more favorable.

Here, a method for calculating the degree of crystallinity of the phosphorus pentasulfide composition will be described with reference to FIG. FIG. 3 is a diagram showing an X-ray diffraction spectrum for explaining a method (peak separation method) for calculating the crystallinity of the phosphorus pentasulfide composition according to this embodiment.
First, in X-ray diffraction using CuKα rays as a radiation source, the diffraction curve corresponding to crystalline has a sharp peak, and the diffraction curve corresponding to amorphous has a broad halo due to scattering. The ratio of crystalline to total amorphous can be calculated as the degree of crystallinity.
In this embodiment, a peak separation method is used as a method for calculating the degree of crystallinity. Separating the peaks of the X-ray diffraction pattern (also called the scattering curve) into a crystalline diffraction curve and an amorphous halo using a profile fitting technique without considering the effects of incoherent scattering, lattice disturbance, etc. . Analysis software attached to the X-ray diffractometer can be used for profile fitting.
A specific procedure for calculating the degree of crystallinity is as follows (see FIG. 3; Rigaku, X-ray diffraction handbook, February 21, 2000, 3rd edition, P83, citing FIG. 3.6.2).
(1) Separation of background A straight line connects the X-ray intensities from the low angle side to the high angle side, and the area under the straight line is taken as the background.
(2) Separation of halos A halo pattern due to amorphous is estimated, and the halos are separated from the background-subtracted scattering curve.
(3) Separation of crystalline diffraction curve A crystalline diffraction curve is separated by the same method as in (2) above.
(4) Calculation of crystallinity Using the area (integrated intensity) under the diffraction curve of the amorphous component (amorphous halo) and the diffraction curve of the crystalline component (crystalline diffraction curve) separated from the scattering curve , the degree of crystallinity is calculated from the following formula (2).
Xc={Ic/(Ic+Ia)}×100 (2)
Ic: area under the diffraction curve of the crystalline component (crystalline diffraction curve) (integrated intensity)
Ia: Area (integrated intensity) under the diffraction curve of the amorphous component (amorphous halo)
Moreover, when the diphosphorus pentasulfide composition contains a solvent, it is preferable to dry and remove the solvent from the diphosphorus pentasulfide composition before measurement.

That is, the diphosphorus pentasulfide composition according to the present embodiment has a crystallinity calculated from the X-ray diffraction spectrum of the above lower limit or more and the above upper limit or less, so that the recovery rate of the diphosphorus pentasulfide composition is and the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material produced using the phosphorus pentasulfide composition.

In the present embodiment, the diphosphorus pentasulfide composition whose crystallinity calculated from the X-ray diffraction spectrum is equal to or higher than the lower limit and equal to or lower than the upper limit is obtained by, for example, heat-treating the starting diphosphorus pentasulfide composition. can be obtained by, for example, reducing the amount of low-boiling phosphorus sulfide compounds ( _P4S3 , _{P4S7 ,} etc.) in the phosphorus pentasulfide _composition .

The diphosphorus pentasulfide composition according to the present embodiment has an endothermic peak in the temperature range of 280° C. or higher and 300° C. or lower in the DSC curve of the diphosphorus pentasulfide composition obtained by measurement with a differential scanning calorimeter. The heat of fusion at the endothermic peak is 60 J/g or more, preferably 65 J/g or more, more preferably 70 J/g or more. The upper limit of the heat of fusion at the endothermic peak is preferably 120 J/g or less, more preferably 110 J/g or less, still more preferably 100 J/g or less.
Here, the endothermic peak observed in the temperature range of 280° C. or higher and 300° C. or lower is the melting point of diphosphorus pentasulfide (P ₂ S ₅ ).

The DSC curve can be measured, for example, by the following method.
First, in an argon atmosphere, 20 to 25 mg of a phosphorus pentasulfide composition is weighed into an aluminum pan, which is then covered with an aluminum lid and sealed with a sample sealer. The reference aluminum container is empty. Differential scanning calorimetry is performed using a differential scanning calorimeter under the conditions of a starting temperature of 25° C., a measurement temperature range of 30 to 350° C., a heating rate of 5° C./min, and an argon atmosphere of 100 ml/min. The differential scanning calorimeter is not particularly limited, but for example, DSC6300 manufactured by Seiko Instruments Inc. can be used.
Moreover, when the diphosphorus pentasulfide composition contains a solvent, it is preferable to dry and remove the solvent from the diphosphorus pentasulfide composition before measurement.
From the DSC curve thus obtained, the presence or absence of an endothermic peak in the temperature range of 280° C. or higher and 300° C. or lower can be observed.
Here, the heat of fusion of the endothermic peak is calculated by determining the area surrounded by the endothermic melting curve including the endothermic peak and the baseline. Since the intrinsic heat capacity of a substance differs before and after the heat change, the baselines before and after the endothermic peak are not aligned.
Therefore, in the present embodiment, the baseline at the endothermic peak is the line connecting point R and point S shown in FIG. Point R is the intersection point of the melting endothermic curve and a line parallel to the Y-axis passing through the intersection point P of the baseline before the endothermic peak and the tangent line of the endothermic peak. Point S is the intersection of the melting endothermic curve and a line parallel to the Y-axis passing through the intersection Q of the baseline after the endothermic peak and the tangent line of the endothermic peak.
In the phosphorus pentasulfide composition according to the present embodiment, usually one endothermic peak is observed in the temperature range of 280°C or higher and 300°C or lower.

In the diphosphorus pentasulfide composition according to the present embodiment, an endothermic peak is observed in the temperature range of 280° C. or higher and 300° C. or lower in the DSC curve, and the heat of fusion of the endothermic peak is at least the lower limit value. The lithium ion conductivity of the sulfide-based inorganic solid electrolyte material obtained can be improved.
Although the reason for this is not necessarily clear, the structure of the raw material phosphorus pentasulfide composition is temporarily destabilized by heating the phosphorus pentasulfide composition according to the present embodiment at a temperature lower than the melting point. It is easy to change _the glassy state of phosphorus pentasulfide _to a more stable _crystalline state _. It is believed that this is because the content of phosphorus compounds (P ₄ S ₃ , P ₄ S _{7 ,} etc.) can be reduced and higher-purity phosphorus pentasulfide can be obtained.
Therefore, the heat of fusion of the endothermic peak measured by the above method represents an index of the amount of low-boiling phosphorus sulfide compounds ( _P4S3 , _{P4S7 ,} etc.) in the _phosphorus pentasulfide composition. It is thought that there are That is, it is considered that the higher the heat of fusion at the endothermic peak, the higher the crystallinity of phosphorus pentasulfide and the lower the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S ₇ , etc.).
For the above reasons, the diphosphorus pentasulfide composition according to the present embodiment contains a small amount of a low-boiling phosphorus sulfide compound. It is believed that the lithium ion conductivity of the solid electrolyte material can be improved.
In the present embodiment, a diphosphorus pentasulfide composition in which an endothermic peak is observed in a temperature range of 280° C. or higher and 300° C. or lower in a DSC curve such as that shown in FIG. 4, and the heat of fusion of the endothermic peak is equal to or higher than the lower limit. is, for example, the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S _7, etc.) in the raw material phosphorus pentasulfide composition by heat-treating it. can be obtained by performing a process for reducing the

The diphosphorus pentasulfide composition according to the present embodiment can further improve the lithium ion conductivity of the obtained sulfide-based inorganic solid electrolyte material. It is preferable that no exothermic peak is observed in the above DSC curve, and it is more preferable that no exothermic peak is observed in the temperature range of at least 30° C. or higher and 280° C. or lower.
In the present embodiment, the fact that no exothermic peak is observed in the DSC curve means that no peak with a heat quantity of 0.3 J/g or more, preferably 0.1 J/g or more is observed.
In the present embodiment, the heat quantity of the exothermic peak and the baseline of the exothermic peak can be defined in the same manner as the heat quantity of the endothermic peak and the baseline of the endothermic peak.
In the present embodiment, the diphosphorus pentasulfide composition in which no exothermic peak is observed in the above temperature range in the DSC curve is obtained, for example, by subjecting the starting diphosphorus pentasulfide composition to heat treatment. It can be obtained by performing a treatment to reduce the amount of low-boiling phosphorus sulfide compounds (P ₄ S ₃ , P ₄ S _7, etc.) in the substance.

The diphosphorus pentasulfide composition according to the present embodiment contains diphosphorus pentasulfide (P ₂ S ₅ ) as a main component. In _the phosphorus pentasulfide composition according to _the present embodiment, components contained _in addition to _phosphorus pentasulfide ( _P2S5 ) include _P4S9 , _P4S7 and _P4S3 .
At this time, the lower limit of the content of diphosphorus pentasulfide contained in the phosphorus pentasulfide composition according to this embodiment is P ₂ S ₅ , P ₄ S ₉ and P ₄ S ₇ in the phosphorus sulfide composition. and P ₄ S ₃ is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, when the total content of P 4 S 3 is 100% by mass. When the lower limit of the content of diphosphorus pentasulfide is at least the above lower limit, the lithium ion conductivity of the resulting sulfide-based inorganic solid electrolyte material can be further improved. Although the upper limit of the content of phosphorus pentasulfide contained in the phosphorus pentasulfide composition according to the present embodiment is not particularly limited, it is, for example, 100% by mass or less.
The content of diphosphorus pentasulfide contained in the phosphorous pentasulfide composition can be calculated, for example, from a solid-state ³¹ P-NMR spectrum.

A solid-state ³¹ P-NMR spectrum can be measured, for example, by the following method.
First, a test sample was filled in a 3.2 mm diameter measurement sample tube in a glove box purged with _N gas, and rotated at a magic angle (54.7 degrees) with respect to an external magnetic field (Magic Angle Spinning : MAS) and measured under the following conditions.
Apparatus: JNM-ECA-600 manufactured by JEOL RESONANCE Co., Ltd.
Observation frequency: 242.95MHz
Pulse width: 90° pulse Pulse waiting time: 2800 seconds Accumulation times: 64 times Measurement mode: Single pulse method MAS speed: 12 kHz
Reference material: ( _NH4 ) _{2HPO4 1.33} ppm
試験試料の^３１ Ｐ－ＮＭＲスペクトルにおいて検出されたピークについて、参考文献１「Ｈｅｌｌｍｕｔ Ｅｃｋｅｒｔ， Ｃｈｅｒｙｌ Ｓ． Ｌｉａｎｇ ａｎｄ Ｇａｌｅｎ Ｄ． Ｓｔｕｃｋｙ ： ^３１ Ｐ ｍａｇｉｃ ａｎｇｌｅ ｓｐｉｎｎｉｎｇ ＮＭＲ ｏｆ ｃｒｙｓｔａｌｌｉｎｅ ｐｈｏｓｐｈｏｒｏｕｓ ｓｕｌｆｉｄｅｓ． Ｃｏｒｒｅｌａｔｉｏｎ ｏｆ ^３１ Ｐ ｃｈｅｍｉｃａｌ ｓｈｉｅｌｄｉｎｇ ｔｅｎｓｏ with local environments, J. Phys. Chem, 1989, 93, 452-457", waveform separation using a Gaussian function is performed based on the following peak assignments, and the integral value of each peak is calculated. The integrated value of the peak derived from each component is proportional to the number of moles of phosphorus contained. Therefore, the content ratio can be calculated from the obtained integrated value and the molecular weight of each component.
P ₂ S ₅ chemical shift 40-52 ppm, P ₄ S ₉ chemical shift 52-70 ppm, P ₄ S ₇ chemical shift 80-90 ppm, 90-100 ppm, 110-115 ppm, P ₄ S ₃ chemical shift Shifts are 80-90 ppm, 90-100 ppm.

In the phosphorus pentasulfide composition according to the present embodiment, it is preferable that no peaks be observed in the range of 52 ppm or more and 70 ppm or less when the solid-state ³¹ P-NMR spectrum is measured. That is, it is preferable that the P ₄ S ₉ peak is not observed. Thereby, the ratio of diphosphorus pentasulfide in the phosphorus pentasulfide composition can be increased, and the lithium ion conductivity of the resulting sulfide-based inorganic solid electrolyte material can be further improved.

In the phosphorus pentasulfide composition according to the present embodiment, it is preferable that no peaks be observed in the range of 80 ppm to 90 ppm when the solid-state ³¹ P-NMR spectrum is measured. That is, it is preferable that the P ₄ S ₇ and P ₄ S ₃ peaks are not observed. Thereby, the ratio of diphosphorus pentasulfide in the phosphorus pentasulfide composition can be increased, and the lithium ion conductivity of the resulting sulfide-based inorganic solid electrolyte material can be further improved.

Examples of the properties of the phosphorus pentasulfide composition according to the present embodiment include powder. Since the sulfide-based inorganic solid electrolyte material described later is generally produced in a dry process, if the diphosphorus pentasulfide composition according to the present embodiment is powdery, the sulfide-based inorganic solid electrolyte material is produced. Easier to manufacture.

[Sulfide-based inorganic solid electrolyte material]
The sulfide-based inorganic solid electrolyte material according to this embodiment will be described below.
The sulfide-based inorganic solid electrolyte material according to the present embodiment is obtained by using, as raw materials, a raw material composition for a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide. be able to. That is, the sulfide-based inorganic solid electrolyte material according to the present embodiment is a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide. It preferably contains objects.

The sulfide-based inorganic solid electrolyte material according to the present embodiment contains Li, P and S as constituent elements from the viewpoint of further improving electrochemical stability, stability in moisture and air, handleability, etc. is preferred.
In addition, the sulfide-based inorganic solid electrolyte material according to the present embodiment further improves lithium ion conductivity, electrochemical stability, stability in moisture and air, handleability, etc., and the sulfide The molar ratio Li/P of the content of Li to the content of P in the inorganic solid electrolyte material is preferably 1.0 or more and 5.0 or less, more preferably 2.0 or more and 4.0 or less. more preferably 2.5 or more and 3.8 or less, still more preferably 2.8 or more and 3.6 or less, still more preferably 3.0 or more and 3.5 or less, still more preferably 3.1 or more and 3.4 or less, particularly preferably 3.1 or more and 3.3 or less, and the molar ratio S/P of the S content to the P content is preferably 2.0 or more and 6 .0 or less, more preferably 3.0 or more and 5.0 or less, still more preferably 3.5 or more and 4.5 or less, still more preferably 3.8 or more and 4.2 or less, still more preferably is 3.9 or more and 4.1 or less, particularly preferably 4.0.
Here, the contents of Li, P and S in the sulfide-based inorganic solid electrolyte material according to the present embodiment can be determined by, for example, ICP emission spectroscopic analysis or X-ray analysis.

In the sulfide-based inorganic solid electrolyte material according to this embodiment, the lithium ion conduction of the sulfide-based inorganic solid electrolyte material by the AC impedance method under the measurement conditions of 27.0 ° C., an applied voltage of 10 mV, and a measurement frequency range of 0.1 Hz to 7 MHz. The degree is preferably 1.0×10 ⁻³ S·cm ⁻¹ or more, more preferably 1.1×10 ⁻³ S·cm −1 or more, and still more preferably 1.3×10 ⁻³ S·cm ⁻¹ or more ^{. 1} or more, particularly preferably 1.5×10 ⁻³ S·cm ⁻¹ or more.
When the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material according to the present embodiment is at least the above lower limit, a lithium ion battery with even better battery characteristics can be obtained. Furthermore, by using such a sulfide-based inorganic solid electrolyte material, it is possible to obtain a lithium ion battery with even better input/output characteristics.

The shape of the sulfide-based inorganic solid electrolyte material according to the present embodiment may be, for example, particulate.
The size of the particulate sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited, but the lower limit of the median diameter _d50 in the volume-based particle size distribution measured by the laser diffraction scattering particle size distribution measurement method is preferably 1 μm. 3 μm or more, more preferably 5 μm or more. Favorable handleability can be maintained by setting the median diameter _d50 of the sulfide-based inorganic solid electrolyte material to the above lower limit or more.
The upper limit of the median diameter _d50 is preferably 150 µm or less, more preferably 120 µm or less, and even more preferably 100 µm or less.
Lithium ion conductivity can be further improved by setting the median diameter _d50 of the sulfide-based inorganic solid electrolyte material to the upper limit value or less.

The sulfide-based inorganic solid electrolyte material according to this embodiment preferably has excellent electrochemical stability. Here, the electrochemical stability refers to, for example, the property of being difficult to be oxidized and reduced in a wide voltage range. More specifically, in the sulfide-based inorganic solid electrolyte material according to the present embodiment, the sulfide-based inorganic solid electrolyte material measured under the conditions of a temperature of 25° C., a sweep voltage range of 0 to 5 V, and a voltage sweep rate of 5 mV / sec. is preferably 0.50 μA or less, more preferably 0.20 μA or less, even more preferably 0.10 μA or less, and even more preferably 0.05 μA or less. It is preferably 0.03 μA or less, and particularly preferably 0.03 μA or less.
When the maximum value of the oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is equal to or less than the upper limit, oxidative decomposition of the sulfide-based inorganic solid electrolyte material in the lithium ion battery can be suppressed, which is preferable.
Although the lower limit of the maximum oxidative decomposition current of the sulfide-based inorganic solid electrolyte material is not particularly limited, it is, for example, 0.0001 μA or more.

The sulfide-based inorganic solid electrolyte material according to this embodiment can be used for any application that requires lithium ion conductivity. Among them, the sulfide-based inorganic solid electrolyte material according to the present embodiment is preferably used for lithium ion batteries. More specifically, it is used for positive electrode active material layers, negative electrode active material layers, electrolyte layers and the like in lithium ion batteries. Furthermore, the sulfide-based inorganic solid electrolyte material according to the present embodiment is suitably used for a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer, etc. It is particularly suitably used for a solid electrolyte layer that constitutes a battery.
An example of an all-solid-state lithium ion battery to which the sulfide-based inorganic solid electrolyte material according to the present embodiment is applied is one in which a positive electrode, a solid electrolyte layer, and a negative electrode are laminated in this order.

[Method for producing sulfide-based inorganic solid electrolyte material]
Next, a method for producing a sulfide-based inorganic solid electrolyte material according to this embodiment will be described.
The method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment includes, for example, preparing a raw material composition for a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide. It is preferable to include a step of mechanical processing.
More specifically, the sulfide-based inorganic solid electrolyte material according to this embodiment can be obtained, for example, by a production method including the following steps (A) and (B). Moreover, the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment may further include the following step (C) and step (D), if necessary.
Step (A): Step of preparing a raw material composition for a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment and lithium sulfide Step (B): Sulfide-based inorganic solid electrolyte Step (C ) Step of heating the obtained sulfide-based inorganic solid electrolyte material in a vitreous state to crystallize at least part of it. Step (D): Pulverize, classify, or granulate the obtained sulfide-based inorganic solid electrolyte material. process

(Step (A) of preparing raw material composition for sulfide-based inorganic solid electrolyte material)
First, a raw material composition for a sulfide-based inorganic solid electrolyte material containing the diphosphorus pentasulfide composition according to the present embodiment, which is a raw material, lithium sulfide, and optionally lithium nitride is prepared. Here, the mixing ratio of each raw material in the raw material composition is adjusted so that the resulting sulfide-based inorganic solid electrolyte material has a desired composition ratio.
The method for mixing each raw material is not particularly limited as long as it is a mixing method that can uniformly mix each raw material. Mixers, V-type mixers, etc.), kneaders, twin-screw kneaders, airflow pulverizers, crushers, rotary blade type pulverizers, and the like can be used for mixing.
Mixing conditions such as stirring speed, treatment time, temperature, reaction pressure, and gravitational acceleration applied to the mixture when mixing the raw materials can be appropriately determined according to the throughput of the mixture.

Lithium sulfide used as a raw material is not particularly limited, and commercially available lithium sulfide may be used. For example, lithium sulfide obtained by reaction of lithium hydroxide and hydrogen sulfide may be used. From the viewpoint of obtaining a high-purity sulfide-based inorganic solid electrolyte material and from the viewpoint of suppressing side reactions, it is preferable to use lithium sulfide with few impurities.
Here, in this embodiment, lithium sulfide also includes lithium polysulfide.

Lithium nitride may be used as the raw material. Here, since nitrogen in lithium nitride is discharged into the system as _N2 , by using lithium nitride as an inorganic compound that is a raw material, a sulfide-based inorganic solid containing Li, P, and S as constituent elements It becomes possible to increase only the Li composition in the electrolyte material.
The lithium nitride according to the present embodiment is not particularly limited, and commercially available lithium nitride (e.g., Li ₃ N, etc.) may be used. For example, metal lithium (e.g., Li foil) and nitrogen gas Lithium nitride obtained by the reaction of may be used. From the viewpoint of obtaining a high-purity solid electrolyte material and from the viewpoint of suppressing side reactions, it is preferable to use lithium nitride with few impurities.

(Step (B) of obtaining a sulfide-based inorganic solid electrolyte material in a vitreous state)
Subsequently, by mechanically treating the raw material composition of the sulfide-based inorganic solid electrolyte material, the diphosphorus pentasulfide composition and lithium sulfide, which are raw materials, are vitrified while chemically reacting to form a vitrified sulfide-based inorganic solid electrolyte material. A solid electrolyte material is obtained.

Here, the mechanical treatment is one in which two or more inorganic compounds are allowed to mechanically collide to vitrify while chemically reacting, and examples thereof include mechanochemical treatment. Here, the mechanochemical treatment is a method of vitrification while applying mechanical energy such as shear force or impact force to the target composition.
Moreover, in the step (B), the mechanochemical treatment is preferably a dry mechanochemical treatment from the viewpoint of easily realizing an environment in which moisture and oxygen are removed at a high level.
When the mechanochemical treatment is used, each raw material can be mixed while pulverized into fine particles, so that the contact area of each raw material can be increased. As a result, the reaction of each raw material can be promoted, so that the sulfide-based inorganic solid electrolyte material according to the present embodiment can be obtained more efficiently.

Here, the mechanochemical treatment is a method of vitrification while applying mechanical energy such as shear force, collision force or centrifugal force to the object to be mixed. Devices for vitrification by mechanochemical treatment (hereinafter referred to as vitrification devices) include crushing and dispersing machines such as ball mills, bead mills, vibration mills, turbo mills, mechanofusion, disc mills and roll mills; Rotary/impact pulverizer consisting of a combination of rotation (shear stress) and impact (compressive stress) represented by drills, impact drivers, etc.; A vertical mill etc. are mentioned. Among these, ball mills and bead mills are preferred, and ball mills are particularly preferred, from the viewpoint of being able to efficiently generate very high impact energy. In addition, from the viewpoint of excellent continuous productivity, roll mills; rotary/impact pulverizers consisting of mechanisms that combine rotation (shear stress) and impact (compressive stress) represented by rock drills, vibration drills, impact drivers, etc. high-pressure type gliding rolls; vertical mills such as roller-type vertical mills and ball-type vertical mills are preferred.

Mixing conditions such as rotation speed, treatment time, temperature, reaction pressure, and gravitational acceleration applied to the starting inorganic composition when mechanically treating the raw material composition of the sulfide-based inorganic solid electrolyte material vary depending on the type of the starting inorganic composition. and the amount of processing can be appropriately determined. In general, the faster the rotation speed, the faster the glass formation rate, and the longer the treatment time, the higher the conversion to glass.
Usually, when X-ray diffraction analysis is performed using CuKα rays as a radiation source, if the diffraction peak derived from the raw material disappears or decreases, the raw material composition of the sulfide-based inorganic solid electrolyte material is vitrified, and the desired It can be judged that a sulfide-based inorganic solid electrolyte material is obtained.

Here, in the step (B), the lithium ion conductivity of the sulfide-based inorganic solid electrolyte material is preferably 1.0×10 ⁻⁴ S·cm ⁻¹ or more, more preferably 2.0×10 ⁻⁴ S·cm ⁻¹ or more, still more preferably 3.0×10 ⁻⁴ S·cm ⁻¹ or more, particularly preferably is preferably 4.0×10 ⁻⁴ S·cm ⁻¹ or more. This makes it possible to obtain a sulfide-based inorganic solid electrolyte material with even better lithium ion conductivity.

(Step (C) of crystallizing at least part of the sulfide-based inorganic solid electrolyte material)
Subsequently, by heating the obtained sulfide-based inorganic solid electrolyte material in a glassy state, at least part of the sulfide-based inorganic solid electrolyte material is crystallized to obtain a glass-ceramic state (also called crystallized glass). A sulfide-based inorganic solid electrolyte material is produced. By doing so, it is possible to obtain a sulfide-based inorganic solid electrolyte material with even better lithium ion conductivity.
That is, the sulfide-based inorganic solid electrolyte material according to the present embodiment is preferably in the glass-ceramics state (crystallized glass state) from the viewpoint of excellent lithium ion conductivity.

The temperature for heating the glassy sulfide-based inorganic solid electrolyte material is preferably in the range of 220° C. or higher and 500° C. or lower, and more preferably in the range of 250° C. or higher and 350° C. or lower.
The time for heating the sulfide-based inorganic solid electrolyte material in a glassy state is not particularly limited as long as the sulfide-based inorganic solid electrolyte material in a desired glass-ceramic state can be obtained. It is in the range of 1 hour or more and 24 hours or less, preferably 1 hour or more and 3 hours or less. Although the heating method is not particularly limited, for example, a method using a kiln can be mentioned. The conditions such as temperature and time for such heating can be appropriately adjusted in order to optimize the properties of the sulfide-based inorganic solid electrolyte material according to this embodiment.

Moreover, it is preferable to heat the glassy sulfide-based inorganic solid electrolyte material in, for example, an inert gas atmosphere. This can prevent deterioration (eg, oxidation) of the sulfide-based inorganic solid electrolyte material.
Examples of the inert gas for heating the sulfide-based inorganic solid electrolyte material in a glassy state include argon gas, helium gas, and nitrogen gas. These inert gases preferably have a high purity in order to prevent contamination of the product with impurities. °C or less is particularly preferred. The method of introducing the inert gas into the mixed system is not particularly limited as long as the inside of the mixed system is filled with an inert gas atmosphere. methods and the like.

(Step (D) of pulverizing, classifying, or granulating)
In the method for producing a sulfide-based inorganic solid electrolyte material according to the present embodiment, a step of pulverizing, classifying, or granulating the obtained sulfide-based inorganic solid electrolyte material may be further performed, if necessary. For example, a sulfide-based inorganic solid electrolyte material having a desired median diameter can be obtained by pulverizing to fine particles and then adjusting the median diameter by classification or granulation. The pulverization method is not particularly limited, and known pulverization methods such as mixer, airflow pulverization, mortar, rotary mill, and coffee mill can be used. Moreover, the classification method is not particularly limited, and a known method such as a sieve can be used.
These pulverization or classification are preferably carried out under an inert gas atmosphere or a vacuum atmosphere from the viewpoint of preventing contact with moisture in the air.

In order to obtain the sulfide-based inorganic solid electrolyte material according to the present embodiment, it is important to appropriately adjust each of the above steps. However, the method for producing the sulfide-based inorganic solid electrolyte material according to the present embodiment is not limited to the above method, and by appropriately adjusting various conditions, the sulfide-based inorganic solid electrolyte material according to the present embodiment can be produced. A solid electrolyte material can be obtained.

[Solid electrolyte]
Next, the solid electrolyte according to this embodiment will be described. The solid electrolyte according to this embodiment includes the sulfide-based inorganic solid electrolyte material according to this embodiment.
The solid electrolyte according to the present embodiment is not particularly limited, but as a component other than the sulfide-based inorganic solid electrolyte material according to the present embodiment, for example, the above-described present embodiment within a range that does not impair the object of the present invention It may contain a solid electrolyte material of a different type from the sulfide-based inorganic solid electrolyte material according to .

The solid electrolyte according to this embodiment may contain a solid electrolyte material of a different type from the above-described sulfide-based inorganic solid electrolyte material according to this embodiment. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulation, but is generally used for lithium ion batteries. can be used. For example, inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials that are different from the sulfide-based inorganic solid electrolyte material according to the present embodiment; Organic solid electrolyte materials such as polymer electrolytes can be mentioned.

Examples of the sulfide-based inorganic solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment described above include Li ₂ SP ₂ S ₅ material, Li ₂ S-SiS ₂ material, Li ₂ S - _GeS2 material, _{Li2S - Al2S3} material _{, Li2S - SiS2} - _Li3PO4 material, _Li2SP2S5 - _GeS2 material _{, Li2S} - _{Li2OP 2S5 - SiS2} material, _Li2S - _GeS2 - _{P2S5 - SiS2} material _{, Li2S} - _SnS2 - _{P2S5 - SiS2} material, _{Li2SP2S5 -} Li _3N material, Li ₂ S ₂ +XP ₄ S ₃ material, Li ₂ SP ₂ S ₅ -P ₄ S ₃ material, and the like. These may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these materials, the Li ₂ SP ₂ S ₅ material is preferable from the viewpoint of excellent lithium ion conductivity and stability that does not cause decomposition or the like in a wide voltage range. Here, for example, the Li ₂ SP ₂ S ₅ material is a solid obtained by chemically reacting an inorganic composition containing at least Li ₂ S (lithium sulfide) and P ₂ S ₅ with each other by mechanical treatment. Means electrolyte material.
Here, in this embodiment, lithium sulfide also includes lithium polysulfide.

Examples of the oxide-based inorganic solid electrolyte material include NASICON type materials such as LiTi ₂ (PO ₄ ) ₃ , LiZr ₂ (PO ₄ ) ₃ , LiGe ₂ (PO ₄ ) ₃ , (La _{0.5 + x} Li _{0.5 -3x} ) Perovskite type such as TiO ₃ , Li ₂ O—P ₂ O ₅ materials, Li ₂ O—P ₂ O ₅ —Li ₃ N materials, and the like.
Examples of other lithium-based inorganic solid electrolyte materials include LiPON, LiNbO ₃ , LiTaO ₃ , Li ₃ PO ₄ , LiPO _4-x N _x (where x is 0<x≦1), LiN, LiI, LISICON, and the like. be done.
Furthermore, glass-ceramics obtained by depositing crystals of these inorganic solid electrolytes can also be used as inorganic solid electrolyte materials.

As the organic solid electrolyte material, for example, polymer electrolytes such as dry polymer electrolytes and gel electrolytes can be used.
As the polymer electrolyte, those generally used for lithium ion batteries can be used.

[Solid electrolyte membrane]
Next, the solid electrolyte membrane according to this embodiment will be described.
The solid electrolyte membrane according to this embodiment contains, as a main component, a solid electrolyte containing the above-described sulfide-based inorganic solid electrolyte material according to this embodiment.

The solid electrolyte membrane according to the present embodiment is used, for example, as a solid electrolyte layer that constitutes an all-solid-state lithium ion battery.
An example of an all-solid-state lithium ion battery to which the solid electrolyte membrane according to the present embodiment is applied is one in which a positive electrode, a solid electrolyte layer, and a negative electrode are laminated in this order. In this case, the solid electrolyte layer is composed of a solid electrolyte membrane.

The average thickness of the solid electrolyte membrane according to the present embodiment is preferably 5 μm or more and 500 μm or less, more preferably 10 μm or more and 200 μm or less, and still more preferably 20 μm or more and 100 μm or less. When the average thickness of the solid electrolyte membrane is equal to or greater than the lower limit, it is possible to further suppress the lack of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane. Moreover, the impedance of a solid electrolyte membrane can be further reduced as the average thickness of the said solid electrolyte membrane is below the said upper limit. As a result, the battery characteristics of the obtained all-solid-state lithium ion battery can be further improved.

The solid electrolyte membrane according to this embodiment is preferably a pressure-molded body of a particulate solid electrolyte containing the above-described sulfide-based inorganic solid electrolyte material according to this embodiment. That is, it is preferable to pressurize the particulate solid electrolyte to form a solid electrolyte membrane having a certain strength due to the anchoring effect between the solid electrolyte materials.
By forming a pressure-molded body, the solid electrolytes are bonded to each other, and the strength of the obtained solid electrolyte membrane is further increased. As a result, it is possible to further suppress the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane.

The content of the sulfide-based inorganic solid electrolyte material according to the present embodiment in the solid electrolyte membrane according to the present embodiment is preferably 50% by mass or more, when the entire solid electrolyte membrane is 100% by mass. It is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more. As a result, the contact between the solid electrolytes is improved, and the interfacial contact resistance of the solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane with excellent lithium ion conductivity, the battery characteristics of the obtained all-solid-state lithium ion battery can be further improved.
Although the upper limit of the content of the sulfide-based inorganic solid electrolyte material according to the present embodiment in the solid electrolyte membrane according to the present embodiment is not particularly limited, it is, for example, 100% by mass or less.

The planar shape of the solid electrolyte membrane is not particularly limited, and can be appropriately selected according to the shape of the electrode or current collector. For example, it can be rectangular.

Further, the solid electrolyte membrane according to the present embodiment may contain a binder resin, and the content of the binder resin is preferably less than 0.5% by mass when the solid electrolyte membrane as a whole is 100% by mass. , more preferably 0.1% by mass or less, still more preferably 0.05% by mass or less, and even more preferably 0.01% by mass or less. Further, the solid electrolyte membrane according to this embodiment preferably does not substantially contain a binder resin, and most preferably does not contain a binder resin.
As a result, the contact between the solid electrolytes is improved, and the interfacial contact resistance of the solid electrolyte membrane can be reduced. As a result, the lithium ion conductivity of the solid electrolyte membrane can be further improved. By using such a solid electrolyte membrane with excellent lithium ion conductivity, the battery characteristics of the obtained all-solid-state lithium ion battery can be improved.
The phrase "substantially free of binder resin" means that it may be contained to the extent that the effects of the present embodiment are not impaired. Further, when an adhesive resin layer is provided between the solid electrolyte layer and the positive electrode or the negative electrode, the adhesive resin derived from the adhesive resin layer present in the vicinity of the interface between the solid electrolyte layer and the adhesive resin layer is referred to as the "solid electrolyte It is excluded from "binder resin in the film".

The binder resin refers to a binder generally used in lithium ion batteries to bind between inorganic solid electrolyte materials. Examples include polyvinyl alcohol, polyacrylic acid, carboxymethylcellulose, polytetrafluoro Examples include ethylene, polyvinylidene fluoride, styrene-butadiene rubber, and polyimide.

The solid electrolyte membrane according to the present embodiment can be produced, for example, by depositing a particulate solid electrolyte on the cavity surface of the mold or on the surface of the base material in the form of a film, and then pressing the solid electrolyte deposited in the form of a film. Obtainable.
The method of pressurizing the solid electrolyte is not particularly limited. For example, when the particulate solid electrolyte is deposited on the cavity surface of the mold, pressing is performed using a mold and a pressing mold, and the particulate solid electrolyte is applied to the substrate surface. When it is deposited on the surface, press using a mold and stamping die, roll press, flat plate press, or the like can be used.
The pressure to pressurize the solid electrolyte is, for example, 10 MPa or more and 500 MPa or less.

In addition, if necessary, the inorganic solid electrolyte deposited in the form of a film may be pressurized and heated. When heat and pressure are applied, the solid electrolytes are fused and bonded to each other, and the strength of the obtained solid electrolyte membrane is further increased. As a result, it is possible to further suppress the loss of the solid electrolyte and the occurrence of cracks on the surface of the solid electrolyte membrane.
The temperature for heating the solid electrolyte is, for example, 40° C. or higher and 500° C. or lower.

[Lithium-ion battery]
FIG. 1 is a cross-sectional view showing an example of the structure of a lithium ion battery 100 according to an embodiment of the invention.
A lithium ion battery 100 according to the present embodiment includes, for example, a positive electrode 110 including a positive electrode active material layer 101 , an electrolyte layer 120 , and a negative electrode 130 including a negative electrode active material layer 103 . At least one of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 contains the sulfide-based inorganic solid electrolyte material according to this embodiment. Moreover, all of the positive electrode active material layer 101, the negative electrode active material layer 103, and the electrolyte layer 120 preferably contain the sulfide-based inorganic solid electrolyte material according to this embodiment. In this embodiment, a layer containing a positive electrode active material is referred to as a positive electrode active material layer 101 unless otherwise specified. The positive electrode 110 may further include a current collector 105 in addition to the positive electrode active material layer 101 or may not include the current collector 105 as necessary. In this embodiment, a layer containing a negative electrode active material is referred to as a negative electrode active material layer 103 unless otherwise specified. The negative electrode 130 may further include a current collector 105 in addition to the negative electrode active material layer 103 or may not include the current collector 105 as necessary.
The shape of the lithium-ion battery 100 according to this embodiment is not particularly limited, and may be cylindrical, coin-shaped, rectangular, film-shaped or any other shape.

The lithium ion battery 100 according to this embodiment is manufactured according to a generally known method. For example, the positive electrode 110, the electrolyte layer 120, and the negative electrode 130 are stacked to form a cylindrical shape, coin shape, square shape, film shape, or any other shape, and if necessary, by enclosing a non-aqueous electrolyte solution. produced.

(positive electrode)
The positive electrode 110 is not particularly limited, and one commonly used in lithium ion batteries can be used. Although the positive electrode 110 is not particularly limited, it can be manufactured according to a generally known method. For example, it can be obtained by forming a positive electrode active material layer 101 containing a positive electrode active material on the surface of a current collector 105 such as an aluminum foil.
The thickness and density of the positive electrode active material layer 101 are not particularly limited because they are appropriately determined according to the intended use of the battery, and can be set according to generally known information.

The positive electrode active material layer 101 contains a positive electrode active material.
The positive electrode active material is not particularly limited, and generally known materials can be used. For example, lithium cobalt oxide (LiCoO ₂ ), lithium nickel oxide (LiNiO ₂ ), lithium manganese oxide (LiMn ₂ O ₄ ), solid solution oxide (Li ₂ MnO ₃ —LiMO ₂ (M=Co, Ni, etc.) ), lithium-manganese-nickel oxide (LiNi _1/3 Mn _1/3 Co _1/3 O ₂ ), composite oxides such as olivine-type lithium phosphorous oxide (LiFePO ₄ ); highly conductive oxides such as polyaniline and polypyrrole; Molecules: Li ₂ S, CuS, Li—Cu—S compounds, TiS ₂ , FeS, MoS ₂ , Li—Mo—S compounds, Li—Ti—S compounds, Li—VS compounds, Li—Fe—S compounds sulfide-based positive electrode active materials such as; sulfur-impregnated acetylene black, sulfur-impregnated porous carbon, mixed powder of sulfur and carbon, and other materials using sulfur as an active material; These positive electrode active materials may be used individually by 1 type, and may be used in combination of 2 or more type.
Among these, a sulfide-based positive electrode active material is preferable from the viewpoint of having a higher discharge capacity density and more excellent cycle characteristics, and Li-Mo-S compounds, Li-Ti-S compounds, Li-VS One or two or more selected from compounds are more preferable.

Here, the Li--Mo--S compound contains Li, Mo, and S as constituent elements, and usually an inorganic composition containing molybdenum sulfide and lithium sulfide, which are raw materials, are chemically treated with each other by mechanical treatment. It can be obtained by reacting.
In addition, the Li—Ti—S compound contains Li, Ti, and S as constituent elements, and usually an inorganic composition containing titanium sulfide and lithium sulfide, which are raw materials, is chemically reacted with each other by mechanical treatment. can be obtained by
The Li—V—S compound contains Li, V, and S as constituent elements, and is usually produced by chemically reacting inorganic compositions containing vanadium sulfide and lithium sulfide, which are raw materials, with each other by mechanical treatment. can be obtained by

Although the positive electrode active material layer 101 is not particularly limited, it may contain one or more materials selected from binder resins, thickeners, conductive aids, solid electrolyte materials, etc., as components other than the positive electrode active material. . Each material will be described below.

The positive electrode active material layer 101 may contain a binder resin that serves to bind the positive electrode active materials together and the positive electrode active material and the current collector 105 .
The binder resin according to the present embodiment is not particularly limited as long as it is a normal binder resin that can be used for lithium ion batteries. Butadiene-based rubber, polyimide, and the like can be mentioned. These binders may be used individually by 1 type, and may be used in combination of 2 or more types.

The positive electrode active material layer 101 may contain a thickening agent in order to ensure the fluidity of the slurry suitable for coating. The thickening agent is not particularly limited as long as it is a normal thickening agent that can be used for lithium ion batteries. Examples thereof include water-soluble polymers such as polycarboxylic acid, polyethylene oxide, polyvinylpyrrolidone, polyacrylate, and polyvinyl alcohol. These thickeners may be used singly or in combination of two or more.

The positive electrode active material layer 101 may contain a conductive aid from the viewpoint of improving the conductivity of the positive electrode 110 . The conductive aid is not particularly limited as long as it is a normal conductive aid that can be used in lithium ion batteries, and examples thereof include carbon black such as acetylene black and ketjen black, and carbon materials such as vapor grown carbon fiber. .

The positive electrode according to the present embodiment may contain a solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment described above, or a different type of solid electrolyte from the sulfide-based inorganic solid electrolyte material according to the present embodiment. A solid electrolyte containing a solid electrolyte material may be included. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulation, but is generally used for lithium ion batteries. can be used. Examples include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; and organic solid electrolyte materials such as polymer electrolytes. More specifically, the inorganic solid electrolyte materials mentioned in the description of the solid electrolyte according to this embodiment can be used.

The mixing ratio of various materials in the positive electrode active material layer 101 is not particularly limited because it is appropriately determined according to the intended use of the battery, and can be set according to generally known information.

(negative electrode)
The negative electrode 130 is not particularly limited, and those commonly used in lithium ion batteries can be used. Although the negative electrode 130 is not particularly limited, it can be manufactured according to a generally known method. For example, it can be obtained by forming a negative electrode active material layer 103 containing a negative electrode active material on the surface of a current collector 105 such as copper.
The thickness and density of the negative electrode active material layer 103 are not particularly limited because they are appropriately determined according to the intended use of the battery, and can be set according to generally known information.

The negative electrode active material layer 103 contains a negative electrode active material.
The negative electrode active material is not particularly limited as long as it is a normal negative electrode active material that can be used for the negative electrode of a lithium ion battery. Examples include natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon. Carbonaceous materials such as; lithium, lithium alloys, tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, aluminum alloys, etc.; metallic materials such as polyacene, polyacetylene, polypyrrole, etc. conductive polymer; lithium-titanium composite oxide (e.g., Li ₄ Ti ₅ O ₁₂ ), and the like. These negative electrode active materials may be used singly or in combination of two or more.

Although the negative electrode active material layer 103 is not particularly limited, it may contain, as components other than the negative electrode active material, one or more materials selected from, for example, binder resins, thickeners, conductive aids, solid electrolyte materials, and the like. . Although these materials are not particularly limited, for example, the same materials as those used for the positive electrode 110 described above can be used.
The mixing ratio of various materials in the negative electrode active material layer 103 is not particularly limited because it is appropriately determined according to the intended use of the battery, and can be set according to generally known information.

The negative electrode according to the present embodiment may contain a solid electrolyte containing the above-described sulfide-based inorganic solid electrolyte material according to the present embodiment, or a type different from the sulfide-based inorganic solid electrolyte material according to the present embodiment. A solid electrolyte containing a solid electrolyte material may be included. The type of solid electrolyte material different from the sulfide-based inorganic solid electrolyte material according to the present embodiment is not particularly limited as long as it has ion conductivity and insulation, but is generally used for lithium ion batteries. can be used. Examples include inorganic solid electrolyte materials such as sulfide-based inorganic solid electrolyte materials, oxide-based inorganic solid electrolyte materials, and other lithium-based inorganic solid electrolyte materials; and organic solid electrolyte materials such as polymer electrolytes. More specifically, the inorganic solid electrolyte materials mentioned in the description of the solid electrolyte according to this embodiment can be used.

(Electrolyte layer)
Next, the electrolyte layer 120 is described. The electrolyte layer 120 is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103 .
The electrolyte layer 120 includes a separator impregnated with a non-aqueous electrolyte and a solid electrolyte layer containing a solid electrolyte.

The separator according to the present embodiment is not particularly limited as long as it has the function of electrically insulating the positive electrode 110 and the negative electrode 130 and allowing lithium ions to pass through. For example, a porous film can be used.

A microporous polymer film is preferably used as the porous membrane, and examples of the material include polyolefin, polyimide, polyvinylidene fluoride, polyester and the like. In particular, porous polyolefin films are preferred, and specific examples include porous polyethylene films, porous polypropylene films, and the like.

The non-aqueous electrolytic solution is obtained by dissolving an electrolyte in a solvent.
Any known lithium salt can be used as the electrolyte, and the electrolyte may be selected according to the type of the active material. For example, _LiClO4 , _LiBF6 , _{LiPF6 , LiCF3SO3} , _LiCF3CO2 , _LiAsF6 , _{LiSbF6 , LiB10Cl10} , _{LiAlCl4 ,} LiCl, LiBr, LiB( _C2H5 ) _{4 , CF3} SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, lithium lower fatty acid carboxylate, and the like.

The solvent for dissolving the electrolyte is not particularly limited as long as it is commonly used as a liquid for dissolving the electrolyte. Ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC). , diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other carbonates; γ-butyrolactone, γ-valerolactone and other lactones; trimethoxymethane, 1,2-dimethoxyethane, diethyl ether Ethers such as , 2-ethoxyethane, tetrahydrofuran, and 2-methyltetrahydrofuran; sulfoxides such as dimethylsulfoxide; oxolanes such as 1,3-dioxolane and 4-methyl-1,3-dioxolane; acetonitrile, nitromethane, formamide, Nitrogen-containing compounds such as dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and ethyl propionate; phosphate triesters and diglymes; triglymes; sulfolane, methylsulfolane, etc. sulfolanes; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propanesultone, 1,4-butanesultone and naphthsultone; These may be used individually by 1 type, and may be used in combination of 2 or more type.

The solid electrolyte layer according to this embodiment is a layer formed between the positive electrode active material layer 101 and the negative electrode active material layer 103, and is a layer formed of a solid electrolyte containing a solid electrolyte material. The solid electrolyte contained in the solid electrolyte layer is not particularly limited as long as it has lithium ion conductivity. It is preferably an electrolyte.
The content of the solid electrolyte in the solid electrolyte layer according to the present embodiment is not particularly limited as long as the desired insulation is obtained. Above all, it is preferable to be in the range of 50% by volume or more and 100% by volume or less. In particular, in the present embodiment, it is preferable that the solid electrolyte layer is composed only of the solid electrolyte containing the sulfide-based inorganic solid electrolyte material according to the present embodiment.

Moreover, the solid electrolyte layer according to the present embodiment may contain a binder resin. By containing a binder resin, a flexible solid electrolyte layer can be obtained. Examples of the binder resin include fluorine-containing binders such as polytetrafluoroethylene and polyvinylidene fluoride. The thickness of the solid electrolyte layer is, for example, within the range of 0.1 μm to 1000 μm, preferably within the range of 0.1 μm to 300 μm.

Although the embodiments of the present invention have been described above, these are examples of the present invention, and various configurations other than those described above can also be adopted.
It should be noted that the present invention is not limited to the above-described embodiments, and includes modifications, improvements, etc. within the scope of achieving the object of the present invention.

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

[1] Production of P ₂ S ₅ <Example 1>
As a raw material diphosphorus pentasulfide composition, diphosphorus pentasulfide manufactured by Perimeter Solutions (product name: Normal/S, melting point: 289.9°C, crystallinity: 31%) was used.
Next, the raw material diphosphorus pentasulfide composition was placed in a quartz container and set in a vacuum heating apparatus (manufactured by Furukawa Co., Ltd.). Then, after repeating the vacuum gas replacement three times, heating was carried out at 200° C. for 7 hours under an Ar gas flow of 10 ml/min. Next, the components collected at the bottom of the quartz vessel were collected and ground in an agate mortar for 5 minutes to obtain a high crystallinity phosphorus pentasulfide composition 1. Each evaluation was performed on the obtained high crystallinity phosphorus pentasulfide composition 1. Table 1 shows the results obtained.

<Example 2>
As a raw material diphosphorus pentasulfide composition, diphosphorus pentasulfide manufactured by LIAONING RUIXING CHEMICAL GROUP (product name: SUPERIOR GRADE Powder, melting point: 287.6°C, crystallinity: 16.6%) was used.
Next, the raw material diphosphorus pentasulfide composition was placed in a quartz container and set in a vacuum heating apparatus (manufactured by Furukawa Co., Ltd.). Then, after repeating the vacuum gas replacement three times, heating was carried out at 200° C. for 7 hours under an Ar gas flow of 10 ml/min. Next, the components collected at the bottom of the quartz vessel were collected and ground in an agate mortar for 5 minutes to obtain a high crystallinity phosphorus pentasulfide composition 2. Each evaluation was performed on the obtained high-crystallinity diphosphorus pentasulfide composition 2. Table 1 shows the results obtained.

<Comparative Example 1>
As a raw material diphosphorus pentasulfide composition, diphosphorus pentasulfide manufactured by LIAONING RUIXING CHEMICAL GROUP (product name: SUPERIOR GRADE Powder, melting point: 287.6°C, crystallinity: 16.6%) was used.
Next, the raw material diphosphorus pentasulfide composition was placed in a quartz container and set in a vacuum heating apparatus (manufactured by Furukawa Co., Ltd.). Then, vacuum heating was performed at 300° C. for 2 hours under a reduced pressure of −0.094 MPa. Next, the components collected at the bottom of the quartz container were collected and ground in an agate mortar for 5 minutes to obtain a phosphorus pentasulfide composition 3. Each evaluation was performed on the obtained phosphorus pentasulfide composition 3. Table 1 shows the results obtained.

<Comparative Example 2>
As diphosphorus pentasulfide composition 4, diphosphorus pentasulfide manufactured by LIAONING RUIXING CHEMICAL GROUP (product name: SUPERIOR GRADE Powder, melting point: 287.6°C, crystallinity: 16.6%) was used as it was. Each evaluation was performed on diphosphorus pentasulfide composition 4. Table 1 shows the results obtained.

Here, the phosphorus pentasulfide composition manufactured by LIAONING RUIXING CHEMICAL GROUP used in Examples and Comparative Examples is sold as a high-purity grade.
again,

[2] Production of sulfide-based inorganic solid electrolyte material A sulfide-based inorganic solid electrolyte material was produced by the following procedure.
Li ₂ S powder (manufactured by Furukawa Co., Ltd., purity 99.9%), Li ₃ N powder (manufactured by Furukawa Co., Ltd.) and P ₂ S ₅ powder are used as raw materials, and the P ₂ S ₅ powder is The high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example were used.
First, a rotary blade pulverizer and an alumina pot (400 mL internal volume) were placed in the glove box, and then high-purity dry argon gas (H ₂ O<1 ppm, O ₂ <1 ppm) injection and vacuum degassing were performed three times.
Then, in a glove box, using a rotary blade pulverizer (rotation speed 18000 rpm), Li ₂ S powder, P ₂ S ₅ powder, and Li ₃ N powder (Li ₂ S: P ₂ S ₅ : Li ₃ N = 71.1: 23.7: 5.3 (mol%)) by mixing a total of 5 g (mixing for 10 seconds and standing for 10 seconds 10 times (cumulative mixing time: 100 seconds)), A raw inorganic composition was prepared.

Subsequently, the starting inorganic composition and 500 g of ZrO ₂ balls with a diameter of 10 mm were put into an alumina pot (inner volume: 400 mL) in the glove box, and the pot was sealed.
Next, remove the alumina pot from the glove box, attach the alumina pot to a ball mill machine installed in an atmosphere of dry dry air introduced through a membrane air dryer, and mechanochemically treat the raw material at 120 rpm for 500 hours. An inorganic composition was vitrified. Every 48 hours of mixing, the powder attached to the inner wall of the pot was scraped off in the glove box, and after sealing, milling was continued in a dry air atmosphere.
Next, an alumina pot was placed in the glove box, the obtained powder was transferred from the alumina pot to a carbon crucible, and annealed at 290° C. for 2 hours in a heating furnace installed in the glove box.
Each evaluation was performed on the obtained sulfide-based inorganic solid electrolyte material. Table 1 shows the results obtained.

[3] Measurement method In the following examples and comparative examples, the measurement methods for the phosphorus pentasulfide composition and the sulfide-based inorganic solid electrolyte material will be described.

(crystallinity)
First, using an X-ray diffractometer (manufactured by Rigaku, RINT2000), voltage 40 kV, current 40 mA, divergence slit 1°, divergence slit vertical limit 10 mm, scattering slit 1°, light receiving slit 0.3 mm, measurement start angle 3° , X-ray diffraction of the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example by X-ray diffraction analysis under the conditions of a measurement end angle of 90 ° A spectrum was obtained for each. CuKα rays were used as the radiation source. The sample holder was a glass sample plate (Cat No. 9200, sample portion 20 mm x 20 mm, depth 0.5 mm).
Then, the following peak separation method was used to calculate the crystallinity Xc of the diphosphorus pentasulfide compositions obtained in Examples and Comparative Examples from the obtained X-ray diffraction spectra.
First, the peaks of the X-ray diffraction pattern were separated into a crystalline diffraction curve and an amorphous halo using a profile fitting technique without considering the effects of incoherent scattering, lattice disturbance, and the like. Analysis software attached to the X-ray diffractometer (manufactured by Rigaku, product name: integrated powder X-ray analysis software PDXL applied analysis (crystallinity)) was used for profile fitting.
A specific procedure for calculating the degree of crystallinity is as follows (see FIG. 3; Rigaku, X-ray diffraction handbook, February 21, 2000, 3rd edition, P83, citing FIG. 3.6.2).
(1) Separation of Background The X-ray intensities from the low-angle side to the high-angle side were connected by a straight line, and the area under the straight line was taken as the background.
(2) Separation of halos A halo pattern due to amorphous was estimated and halos were separated from the background-subtracted scattering curve.
(3) Separation of crystalline diffraction curve A crystalline diffraction curve was separated in the same manner as in (2) above.
(4) Calculation of crystallinity Using the area (integrated intensity) under the diffraction curve of the amorphous component (amorphous halo) and the diffraction curve of the crystalline component (crystalline diffraction curve) separated from the scattering curve , the crystallinity Xc was calculated from the following formula (2).
Xc={Ic/(Ic+Ia)}×100 (2)
Ic: area under the diffraction curve of the crystalline component (crystalline diffraction curve) (integrated intensity)
Ia: Area (integrated intensity) under the diffraction curve of the amorphous component (amorphous halo)

(heat of fusion/melting point)
A differential scanning calorimeter was used to measure the heat of fusion of the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example.
In an argon atmosphere, 20-25 mg of the phosphorus pentasulfide composition was weighed into an aluminum pan, which was then covered with an aluminum lid and sealed with a sample sealer. The reference aluminum container is empty. Differential scanning calorimetry was performed using a differential scanning calorimeter under conditions of a starting temperature of 25° C., a measurement temperature range of 30 to 350° C., a heating rate of 5° C./min, and an argon atmosphere of 100 ml/min. DSC6300 (manufactured by Seiko Instruments Inc.) was used as a differential scanning calorimeter at this time. At this time, an endothermic peak was observed in the temperature range of 280° C. or higher and 300° C. or lower in the obtained DSC curves in all of the examples and comparative examples.
The amount of heat of fusion was calculated by determining the area surrounded by the melting endothermic curve including the endothermic peak in the temperature range of 280° C. or higher and 300° C. or lower in the DSC curve thus obtained and the baseline.
Also, the peak top of the endothermic peak in the temperature range of 280° C. or higher and 300° C. or lower was measured as the melting point.

(Content of diphosphorus pentasulfide)
The content of phosphorus pentasulfide was measured using a solid ³¹ P-NMR spectrum for the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example. .
First, a test sample was filled in a 3.2 mm diameter measurement sample tube in a glove box purged with _N gas, and rotated at a magic angle (54.7 degrees) with respect to an external magnetic field (Magic Angle Spinning : MAS) and measured under the following conditions.
Apparatus: JNM-ECA-600 manufactured by JEOL RESONANCE Co., Ltd.
Observation frequency: 242.95MHz
Pulse width: 90° pulse Pulse waiting time: 2800 seconds Accumulation times: 64 times Measurement mode: Single pulse method MAS speed: 12 kHz
Reference material: ( _NH4 ) _{2HPO4 1.33} ppm
試験試料の^３１ Ｐ－ＮＭＲスペクトルにおいて検出されたピークについて、参考文献１「Ｈｅｌｌｍｕｔ Ｅｃｋｅｒｔ， Ｃｈｅｒｙｌ Ｓ． Ｌｉａｎｇ ａｎｄ Ｇａｌｅｎ Ｄ． Ｓｔｕｃｋｙ ： ^３１ Ｐ ｍａｇｉｃ ａｎｇｌｅ ｓｐｉｎｎｉｎｇ ＮＭＲ ｏｆ ｃｒｙｓｔａｌｌｉｎｅ ｐｈｏｓｐｈｏｒｏｕｓ ｓｕｌｆｉｄｅｓ． Ｃｏｒｒｅｌａｔｉｏｎ ｏｆ ^３１ Ｐ ｃｈｅｍｉｃａｌ ｓｈｉｅｌｄｉｎｇ ｔｅｎｓｏ with local environments, J. Phys. Chem, 1989, 93, 452-457", waveform separation using a Gaussian function was performed based on the following peak assignments, and the integral value of each peak was calculated.
At this time, the chemical shift of P ₂ S ₅ (P ₄ S ₁₀ ) is 40-52 ppm, the chemical shift of P ₄ S ₉ is 52-70 ppm, the chemical shift of P ₄ S ₇ is 80-90 ppm, 90-100 ppm, 110-110 ppm. 115 ppm, chemical shifts of P ₄ S ₃ were 80-90 ppm, 90-100 ppm.
The ratio of the integrated value of the peak present at 40 to 52 ppm to the total integrated value of each peak was calculated, and the above ratio was taken as the content of diphosphorus pentasulfide.

(median diameter _d50 )
Using a laser diffraction scattering particle size distribution analyzer (Malvern Co., Ltd., Mastersizer 3000), the high crystallinity diphosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example were measured by a laser diffraction scattering method. The particle size distribution of the phosphorus pentasulfide composition was measured. From the measurement results, the median diameter _d50 in the volume-based cumulative distribution was determined for the phosphorus pentasulfide composition.

(lithium ion conductivity)
Using the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example, a sulfide-based inorganic solid electrolyte material was produced by the above procedure, and the obtained The lithium ion conductivity of the powder was measured by the AC impedance method.
Potentiostat/galvanostat SP-300 manufactured by Biologic was used to measure the lithium ion conductivity. The size of the sample was 9.5 mm in diameter and 1.2 to 2.0 mm in thickness. The measurement conditions were an applied voltage of 10 mV, a measurement temperature of 27.0°C, a measurement frequency range of 0.1 Hz to 7 MHz, and a Li foil electrode. .
Here, as samples for lithium ion conductivity measurement, the high-crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example were used in the above procedure. to prepare a sulfide-based inorganic solid electrolyte material, and 150 mg of the powder obtained there is pressed at 270 MPa for 10 minutes using a pressing device to obtain a diameter of 9.5 mm and a thickness of 1.2 to 2.0 mm. plate-like sulfide-based inorganic solid electrolyte material.

(Measurement of maximum value of oxidative decomposition current)
Using the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example, a sulfide-based inorganic solid electrolyte material was produced by the above procedure, and the press apparatus 120 to 150 mg of the obtained powder was pressed at 270 MPa for 10 minutes to obtain a plate-like sulfide-based inorganic solid electrolyte material (pellet) having a diameter of 9.5 mm and a thickness of 1.3 mm. Next, Li foils as reference and counter electrodes were press-bonded to one surface of the obtained pellet under conditions of 18 MPa for 10 minutes, and SUS314 foil was adhered to the other surface as a working electrode.
Next, using a Potentiostat/Galvanostat SP-300 manufactured by Biologic Inc., the sulfide-based inorganic solid electrolyte material is oxidatively decomposed under conditions of a temperature of 25° C., a sweep voltage range of 0 to 5 V, and a voltage sweep rate of 5 mV/sec. The maximum value of current was obtained.

(Recovery rate)
Using the mass of the high crystallinity phosphorus pentasulfide composition obtained in the example and the phosphorus pentasulfide composition obtained in the comparative example, and the mass of the raw material phosphorus pentasulfide composition, the following formula ( The recovery rate was calculated from 1).
Recovery rate (%) = (M _A /M _B ) x 100 (1)
M _A : mass (g) of the high crystallinity phosphorus pentasulfide composition
M _B : Mass (g) of raw material phosphorus pentasulfide composition

In the method for producing the diphosphorus pentasulfide composition of the example, both a high degree of crystallinity and a high recovery rate were achieved.
FIG. 2 shows the X-ray diffraction spectra of the phosphorus pentasulfide compositions obtained by the production methods of the phosphorus pentasulfide compositions of Examples and Comparative Examples.
5 shows the DSC curve on the high temperature side, and FIG. 6 shows the DSC curve on the low temperature side.

100 Lithium ion battery 101 Positive electrode active material layer 103 Negative electrode active material layer 105 Current collector 110 Positive electrode 120 Electrolyte layer 130 Negative electrode

Claims (7)

a heating step of heat-treating the starting diphosphorus pentasulfide composition at a temperature of 130° C. or higher and lower than the melting point of the starting diphosphorus pentasulfide composition;
A method for producing a phosphorus pentasulfide composition, wherein a high crystallinity phosphorus pentasulfide composition having a higher degree of crystallinity than the raw material phosphorus pentasulfide composition is obtained. A method for producing the phosphorus pentasulfide composition according to claim 1,
The crystallinity of the high crystallinity diphosphorus pentasulfide composition calculated from the spectrum obtained by X-ray diffraction using CuKα rays as a radiation source is 40% or more and 80% or less.
A method for producing a phosphorus pentasulfide composition. A method for producing the diphosphorus pentasulfide composition according to claim 1 or 2,
A method for producing a phosphorus pentasulfide composition, wherein the high crystallinity phosphorus pentasulfide composition has a recovery rate of 90% or more and 99% or less. A method for producing the phosphorus pentasulfide composition according to any one of claims 1 to 3,
A method for producing a diphosphorus pentasulfide composition, wherein the heating time in the heating step is 0.5 hours or more and 24 hours or less. A method for producing the phosphorus pentasulfide composition according to any one of claims 1 to 4,
A method for producing a diphosphorus pentasulfide composition, wherein the heating temperature in the heating step is 180° C. or higher and 220° C. or lower, and the heating time is 6 hours or longer and 8 hours or shorter. A method for producing the phosphorus pentasulfide composition according to any one of claims 1 to 5,
A method for producing a diphosphorus pentasulfide composition, wherein the heating step is performed in an inert gas atmosphere or in a vacuum atmosphere. A method for producing the phosphorus pentasulfide composition according to claim 6,
The heating step is performed under an inert gas atmosphere,
A method for producing a diphosphorus pentasulfide composition, wherein the inert gas in the inert gas atmosphere is argon gas.

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